Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Quantos motoristas ativos, até 20 de março de 2010, a Dinamarca tem?
 ###Tabelas: CREATE TABLE current_fleet (current_fleet_id AUTO_INCREMENT PRIMARY KEY, Vessel VARCHAR, Built INT, Max Speed VARCHAR, Length VARCHAR, Breadth VARCHAR, Flag VARCHAR, Propulsion VARCHAR) CREATE TABLE player_selection (player_selection_id AUTO_INCREMENT PRIMARY KEY, Year INT, Pick VARCHAR, Player VARCHAR, Position VARCHAR, College VARCHAR) CREATE TABLE forbes_global_2000 (forbes_global_2000_id AUTO_INCREMENT PRIMARY KEY, April 2013 Cum. Rank INT, Name VARCHAR, Rank 2012 INT, Rank 2013 INT, Base VARCHAR, 2013 rev (bil. USD ) VARCHAR, 2013 Profit (mil. USD ) VARCHAR, Assets 2013 (bil.$) VARCHAR, Market cap March 15 (mil.$) INT) CREATE TABLE by_nationality (by_nationality_id AUTO_INCREMENT PRIMARY KEY, Country VARCHAR, Total Drivers INT, Champions INT, Championships INT, Current March 20, 2010 INT, First driver(s) VARCHAR, Last/Current driver(s) March 20, 2010 VARCHAR) CREATE TABLE european_version (european_version_id AUTO_INCREMENT PRIMARY KEY, Song title VARCHAR, Artist VARCHAR, Language VARCHAR, Decade VARCHAR, Genre VARCHAR, Exportable VARCHAR, Family Friendly VARCHAR)  
SELECT Current March 20, 2010 FROM by_nationality WHERE Country = Denmark